9Leibfried T, Feser K. On-line monitoring of transformers by means of the transfer function method[C]. Conference Record of IEEE International Symposium on Electrical Insulation. Pittsburgh, PA, USA.1994:111-114.
10Leibfried T, Feser K. Monitoring of power transformers using the transfer function method[J]. IEEE Transactions on Power Delivery,1999,14(4): 1333-1339.